HATTIESBURG
-
With his upcoming experiment aboard the International Space Station,
chemistry professor Dr. John Pojman of The University of Southern
Mississippi is proving the old adage about necessity being the mother
of invention.

After the recent
Columbia Space Shuttle disaster left NASA without a means of bringing
up new experiments to the Space Station, the agency decided to continue
its research by using items already on board.

"It has
been an orbital scavenger hunt," said Pojman, who has worked
extensively with NASA during the last 10 years, studying polymer
processing and how miscible fluids interact in weightlessness.

"We finally
decided on Russian honey, which the astronauts use with their tea,
and water as our two fluids."

The Miscible
Fluid in Microgravity (MFMG) experiment will test how miscible fluids
- those that completely dissolver in each other - interact without
the interference of gravity. The test, which will be performed this
September by astronauts using unused urine collection syringes and
Zip-lock bags, can only be performed in weightlessness. However,
it does have some down-to-earth implications, Pojman said.

The models
used to simulate the experiment provide information on the fundamental
interactions between molecules, he said. "The results of the
experiment could help us develop improved understanding of processes
ranging from the dissolving of plastics to protein crystal growth."

Immiscible
fluids, like oil and water, exhibit something called "interfacial
tension" because of the different ways that each type of molecule
pulls on each other. "This interfacial (surface) tension is
what allows a water skeeter to walk on water," Pojman explained.

The experiment,
accepted by NASA in April, will test a time-worn but unsupported
theory. "One hundred years ago, a scientist named Korteweg
predicted that miscible fluids could act like immiscible fluids
until they had diffused and become uniform," Pojman said.

"Although
there has been much theory and some provocative experiments during
the intervening century, no definitive experiments have been performed.
This simple experiment will be a step toward a complete test of
Korteweg's hypothesis."

If a stream
of one immiscible fluid is injected into another in weightlessness,
the stream will break into drops - a phenomenon called the Rayleigh-Tomotika
instability. Pojman said his test will determine if the same breakup
occurs with two miscible fluids by injecting honey into water and
observing if the honey stream breaks into drops.

"Because
the honey is denser than water," he said, "the stream
sinks in the water when we try to do the experiment on earth."

Pojman added:
"A drop of immiscible fluid in another fluid will always become
spherical in weightlessness. We will test if an irregular drop of
water injected into honey does the same. To prevent the drop from
floating to the top of the honey, the experiment must be performed
in weightlessness."

Both experiments
will also be performed while heating the fluids to test if miscible
fluids migrate - something that is seen with immiscible drops and
streams.

A veteran of
more than 800 microgravity parabolas aboard NASA's KC-135 research
aircraft, also known as the "Vomit Comet," Pojman has
traveled to NASA's Marshall Space Flight Center several times to
develop the actual crew procedures for the test. The NASA operations
team documented each step of the procedure and has prepared a file
with digital pictures to upload to the Space Station.

Several students
and visitors have also worked on the project, including graduate
students Brian Zoltowski and William Ainsworth, postdoctoral researcher
Dr. Victor Wyatt, and two visitors, Boon Teo of Singapore and Birsen
Varisli of Bolivia.

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April 20, 2004 4:09 PM